Dr. Deborah Ann Hall is applying for a mentored patient-oriented research (K23) award in the area of movement disorders. This proposal describes a research and training program for the development of a clinician-investigator in neurology. The principal investigator, Dr. Hall, has completed neurology residency raining and a movement disorders fellowship. She received a competitive clinical research fellowship from the American Academy of Neurology and is pursuing a Ph.D. in Clinical Science. The candidate's immediate goals are to continue research in the fragile X-associated tremor/ataxia syndrome, by directly applying her newly acquired epidemiologic and biostatistics skills in the proposed project. Her long term goals are to study the genetic risk factors, neuroepidemiology, and treatment of ataxia, including sporadic ataxia. During the award period, Dr. Hall will be based in the Department of Neurology at the University of Colorado (UCDHSC). UCDHSC has an extensive track record for supporting and developing clinician-investigators. The Ph.D. in Clinical Sciences program at UCDHSC facilitates mentored multidisciplinary clinical research. The candidate will carry out her research with Professors Tim Byers MD (Epidemiology), Maureen Leehey MD (Neurology), Gary Zerbe PhD (Biostatistics), and Paul Hagerman MD PhD (Biological Chemistry). Dr. Hall's research program is to determine the prevalence of repeat expansions in the FMR1 (fragile X mental retardation) gene in subjects with tremor, ataxia, and/or parkinsonism. Dr. Hall will do a cross- sectional study by recruiting subjects in her clinics with the three phenotypes and performing PCR of the FMR1 gene. All subjects eligible will be recruited and the genetic testing will be done in a research laboratory. The primary outcomes to be measured are the prevalence of repeat expansions in the three groups combined and each phenotypic subgroup. The age of onset, age of diagnosis of neurological signs, and correlations between trinucleotide repeat size and phenotype are also outcomes to be measured. Linear and logistic regression models will be used and covariates including race and ethnicity will be studied. Relevance: This study is important because it may define genetic risk factors for various abnormal movements, such as tremor. This will result in improved diagnosis and potentially treatment of individuals with progressive neurological diseases. These illnesses represent an important public health problem as they cause morbidity and mortality in our aging population.